Automatic viscometer and process of using same



Jan. 8, 1963 J. J. HEIGL ETAI. 3,071,951

AUTOMATIC VISCOMETER AND PROCESS 0F USING SAME:

Filed Dec. 22, 1959 6 Sheets-Sheet 1 AAAAAAA .A AAAAA AAAAAAAAAA John J. Heigl George E. Conklin Inventors James A. Wilson Jan. 8, 1963 J. J. HEIGL ETAL AUTOMATIC VISCOMETER AND PROCESS OF USING SAME Filed Dec. 22, 1959 6 Sheets-Sheet 2 FIGUR-E 3 John J. Heigl George E. Conklin Inventors James A. Wilson AUTOMATIC VISCOMETER AND PROCESS OF USING SAME Filed Dec. 22, 1959 Jan. 8, 1963 J. J. HEIGL ETAL 6 Sheets-Sheet 3 v mDwC John J. Heigl George E. Conklin Inventors James A. Wilson B Z.;

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Jan. 8, 1963 J. J. HEIGL ETAL 3,071,961

AUTOMATIC VISCOMETER AND PROCESS OF. USING SAME 6 Sheets-Sheet 4` Filed Dec. 22, 1959 mo. w maw won@ m0. v f v N: mo. N NO- mm1* Nw O m mDwE ommt mmt m wm mm r @mlm UN@ m mxrm Nm *Vm .T l Ft@ o m m John J. Hei

Potent Attorney AUTOMATIC vrscoMETER AND PROCESS oF USING SAME Filedneo. 22. 1959 Jan. 8, 1963 J. J. HEIGI. ETAL 6 Sheets-Sheet 5 Jan. 8, 1963 J. J. HElGL ET AL 3,071,961

AUTOMATIC vrscoMETER AND PRocEss oF USING sm:

Filed Dec. 22. 1959 6 Sheets-Sheet 6 mao OQN United States Patent Utilice 3,071,961 Patented Jan. 8, 1963 3,071,961 AUTOMATIC VISCOMETER AND PROCESS OF USING SAME John J. Heigl, Short Hills, George E. Conklin, Stanhope,

and James A. Wilson, Somerset, N J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Dec. 22, 1959, Ser. No. 861,343 9 Claims. (Cl. 73-55) The present invention relates to the carrying out of standard determinations of kinematic viscosities of hydrocarbon oils. More particularly, the invention relates to the determination of such viscosities employing a novel automatic viscometer which conforms, as to results, to the standard kinematic viscometer determination as stated in Standard Procedure ASTM D-445. The capillary type Ubbelohde viscometer has been conventionally used for many years and comprises in essence a capillary tube of standard internal diameter through which the rate of iiow of the particular oil under test is determined by a standard method involving the accurate measurement of time.

In the past, a sample of 4oil whose viscosity was to be determined was charged to the conventional standard apparatus which was then immersed in a water bath or a suitable constant temperature bath to allow the oil to come to equilibrium at the temperature desired for the measurement. This usually was at 100 F. or at 210 F. and sometimes at 130 F. After the oil had reached the equilibrium temperature, suction was applied to the oil to pull it into the standard capillary tube and the oil was allowed to ascend so that it half lled the small bulb at the top of the capillary. The suction was then released and the oil was allowed to flow downwardly through the capillary. When the meniscus of the oil reaches an upper mark, a timing in suitable fractions of a second begins, which timing is stopped when the oil meniscus reaches the capillary tube. By a standard formula, the kinematic viscosity in centistokes is determined. From such viscosity determinations at different temperatures, it is possible to calculate the viscosity index of the oil which is, of course, a standard and conventional inspection tool for determining one of the important properties of oils processed and marketed by the petroleum industry.

In present day refinery operations, particularly in the case of larger refineries, many hundreds of viscosity determinations rnust be made during the course of a day. A considerable number of trained technicians must be kept constantly at the task of making these determinations. This is time-consuming and requires a considerable number of men. Also, because of the fact that the timing is usually done manually, Le., with a stop watch, and depends to some extent on the particular skill and training of the operator, uniformity of determinations is not always possible and so the accuracy in many cases leaves something to be desired, particularly in the hands of the technician who may be incompletely skilled in performing the operation and taking the time measurements.

It is therefore of tremendous importance from the standpoint of accuracy of determination and etiicient utilization of manpower to devise and successfully operate an automatic viscometer of the type herein described. In order to calculate accurately the viscosity index based upon the viscosity determination, it is necessary to have a precision of 0.2% or better. The present invention Vin devising a successful automatic viscometer achievesa speed-up in viscosity determinations, a great saving of skilled manpower, and has accomplished an accuracy at short test times which hasheretofore been unattainable by any previously employed methods for viscosity determinations.

The novel invention may best be described in general terms as follows. be determined at a constant temperature, for example, F. is placed in the same type of capillary viscometer tube as described in standard method designated ASTM D-445. This tube is permanently mounted in a thermostatically controlled constant temperature bath. The lower portion of the viscometer tube extends suiciently below the bath so that it is possible -by the application of vacuum to the top of the capillary to draw the oil lto be tested into the capillary tube. Once the oil has been allowed to come to temperature equilibrium in the constant temperature bath, a system of light sources, each having a corresponding photodetector mounted opposite the light source, is employed for actuating certain electronic equipment, upon the basis of which it is possible to electronically and accurately determine the length of time elapsing between the passage of the oil meniscus through a tirst paired light beam-photodetector arrangement and then through a second paired light beamphotodetector arrangement. The time elapsing between these two positions is translated into electrical impulses which, in turn, are utilized for the activation of an electronic counter mechanism, and with a properly calibrated capillary, it is possible to read in centistokes directly from the electronic counter, the viscosity of the oil under test. Also and somewhat more desirable, it is possible to translate the viscosity in centistokes from the electronic counter by means of an electrically actuated printer to the label attached to the sample bottle containing the oil under test. These variations and a fuller description of the invention will be more fully hereinafter undertaken with reference to the drawings.

The electrical impulses emanating from the photodetectors are ampliiied by means of amplifiers so that they can be used to trigger the operation of the electronic counter. The data read by the counter may be either recorded on tape, visually read and recorded, or printed or stamped on a sample tag 0r on a bottle label. One of the great advantages of the present installation lies in the fact that not only is there a relatively short measuring -time which is accurately determined, but the overall testing time is reduced because the capillary tube is permanently mounted in the constant temperature bath which is maintained at the selected test temperature at all times. Only a very small sample is used so that the soaking time required to bring the oil sample to temperature equilibrium with the constant temperature bath is usually less than three minutes as compared with from 10 to l5 minutes required in a conventional viscosity determination. Also, since the capillary tube does not require handling and has a minimum of surface, the cleaning and drying operation at the conclusion of the test, preparatory -to using the viscometer for another sample, is far less than the time normally required in conventional determinations. Eecause of the fact that so many samples must be tested in 4the course of a day, the minutes and seconds saved in making the determination and preparing the viscometer for the next determination areof tremendous signiticance inthe eliicient utilization of technical manpower in modern petroleum refineries,

Referring now to the drawings for a fuller understanding of the invention, FIGURE. 1 represents a diagrammatic view in partial sectional elevational of a single viscometer and the connections thereto for automatically securing electrical impulses which can be translated into centistokes by Vother equipment described in the additional tigures.

FIGURE 2 represents in plan view and somewhat dia-VV grammatically the manifold 17 shown in FIGURE 1.A

FIGURE 3 is a sectional elevation of the manifold 17 A sample of oil whose viscosity is to 3 shown in the plan view FIGURE 2 and taken along the line III-III of FIGURE 2.

FIGURE 4 is a schematic diagram of a single viscometer installation showing the operation of the electronic control system and of the hydraulic control system for handling the sample bottles.

FIGURE 5 is a diagrammatic elevational view showing the travel pattern through which a sample bottle passes in making two viscosity determinations at two different temperatures.

FIGURE 6 shows schematically and in plan view the printing system together with a portion of the equipment used in recording on the label of the sample bottle the centistoke values for the oil sample whose viscosity has been determined.

FIGURE 7 shows schematically the electronic units and connections employed in operating the first portion of the viscosity determination cycle, namely the introduction f the oil into the viscometer and the holding of the oil in the viscometer for a period of three minutes to bring it ltno tlmperature equilibrium with the constant temperature FIGURE 8 shows schematically the electronic equipment employed to receive the impulses and record in centis'tokes the viscosity of the oil under determination and s hows'in part the electronic system used for recording,- by printing, of the centistoke values on the sample bottle label.

FIGURE 9 schematically shows the electronic equipment required for operating the cleaning cycle for the capillary tube preparatory to introducing a new sample into the system.

Referring now to FIGURE 1, sample bottle 4 containing an oil, whose viscosity is to be determined, is placed under viscometer tube 2 with the oil level being sufficiently above point of the viscometer tube so that by the application of suction the oil will be drawn into the capillary. The capillary tube 2 is placed within water bath 3 which is held at a constant temperature, for example, 100 F. by conventional means (not shown). At points 8, 9, and 10 of capillary tube 2 are light sources 14, 15, and 16, in water tight seals commonly miniature light bulbs and opposite them are photodetectors 14a, 15a, and 16a, also in water tight seals, so positioned that a light beam from a miniature light bulb passes through the glass capillary tube 2 at the respective points 8, 9, and 10 and strikes the light sensitive portions of the detectors 14a, 15a, and 16a. The miniature light bulbs are connected to a conventional source of electricity 26.

A holdup reservoir 11 provides a volume of light oils for ow times sufliciently long to allow accurate measurements of time intervals. Obtaining this volume by means of a reservoir rather than a long tube is desirable to avoid a widely varying liquid head. A working reservoir 12 provides protection against liquid level overshoot on the charging cycle which might otherwise cause contamination of Valve chambers above the capillary tube.

In operating the automatic viscometer at the preselected temperature of 210 F., the photodetectors 14a, 15a, and 16a are placed outside of the constant temperature bath 3 and the light source from the miniature light sources 14, 15, and 16 is transmitted to the photodetectors by means of Lucite or quartz rods which, of course, are capable of transmitting light rays with very little loss in transmission. These are commonly referred to as light pipes and, in the instant installation, are usually metal encased or shielded with a suitable metal such as copper or brass. The light sources may also'be outside of the bath 3 and light pipes employed to conduct the light to points 8, 9, and 10.

The light beam is maintained constant between the light source and the particular photodiode. In other words, the light beam is continuous between 16 and 16a, between 15 and 15a, and between 14 and 14a. The color of the oil is not governing. As long as the oil transmits light and does not contain suspended matter, the straightthrough system depends on the lens effect of the oil in the capillary. The photodetector actuates the appropriate relay in the control system by reason of the differential between high and low intensity light striking its photosensitive area.

In the case of determining the viscosity of oils which are dark in color such as, for example, cutback asphalts, road oils, or oils which contain suspended carbonaceous matter and ywhich might be considered as dirty or dark oils, the light beam source and the photodetector are usually not mounted on oppositesides of the viscometer tube, i.e. at 180 from each other, but are usually offset so that they are mounted at 60, and 45, etc. from each other and so that the light beam passes through only a portion of the total diameter of the oil column in the capillary tube. In this instance, the oil does not act as a light lens, but rather operates the photodetectors by reason of the scatter lens effect.

In preparing to make a viscosity determination and after sample bottle 4 containing the oil to be tested is placed in the position shown in FIGURE l, valve 25 is opened and vacuum is admitted to the system through line 24 connected to manifold 17 which is, in turn, connected to the top of the viscosity capillary tube 2. The oil rises through the dip tube section 6, having a bias tapered end 5, through the section of reduced diameter 7,4 and past the first light beam existing between 14 and 14a at point 8. The vacuum, which may be gradually in creased as oil is soaked into tube capillary 7, is continued until the oil has been drawn to the point where the meniscus of the oil intersects the light beam between 16 and 16a at point 10, at which time the vacuum solenoid valve 25 is closed.

At the time of closing of vacuum solenoid valve 25, vent solenoid valve 23 is opened. After this operation, oil drains from viscometer tube 2 into the sample bottle 4 until the top of the meniscus in tube 2 has reached the point of intersecting light beam 14 and 14a at point 8. This operation is for the purpose of wetting the inner glass surfaces of the capillary. At this time, photodetector 14a is actuated, and by `a system of controls, the electrical impulses from photodetector 14a close solenoid vent valve 23 and at the same time open solenoid vacuum valve 25. The sample is again drawn up into the viscometer tube 2 until the top meniscus of the oil again intersects the light beam between 16 and 16a at point 10, at which time the vacuum solenoid valve 25 is closed. During the foregoing operations, sample bottle 4 is held stationary under the viscometer tube 2 with the lower section of viscometer tube (dip tube 6) immersed in the oil sample in sample bottle 4.

At the closing of the vacuum solenoid valve 25, one timing mechanism is also actuated by a system of controls from the photodetector 16a. The timing mechanism starts a three minute hold and soak cycle during which time the sample in the viscometer tube 2 is allowed to reach the temperature of the bath. During this same period, certain additional operations are carried out. Thus, a second timing mechanism is also actuated at the same time by the system of controls from the photodetector 16a. This second timing mechanism starts a 30 second period during which time the sample bottle 4 is held in position under the viscometer tube 2 with the dip tube 6 immersed in the oil sample in sample bottle 4. The sample bottle 4 is held in this position for this period to allow the oil in the viscometer tube 2 to reach an equilibrium position with the internal vacuum within the upper section of viscometer tube 2 and within the manifold 17. At the end of the 30 second period, the sample bottle 4 is lowered to the point where dip tube 6 is no longer immersed in the oil sample in sample bottle 4. At the end of the above-mentioned 30 second period, a timing mechanism starts a one minute hold cycle, during which time the oil drains from the dip tube 6 section of the viscometer tube 2 into sample bottle 4. At

the completion of the one minute hold cycle, the drain `cup 91 (shown in FIGURE 4) is positioned under viscometer tube 2.

No further operations take place until the completion of the three minute hold-and-soak cycle. At the conrpletioncf the three minute timing cycle, the solenoid vent valve 23 is opened so that the oil is then under `atmospheric pressure. T-he oil then ows downwardly through the capillary tube 2. Once the meniscus intersects the light beam existing between 16 and 16a, photodetector a becomes energized and Will emit an electrical impulse when the rneniscus reaches point 9 in the tube 2. Upon reaching this point, the detector 15a starts the timing mechanism. The timing mechanism' is stopped by a second electrical impulse from 14a which is emitted at point 8 when the oil meniscus passes this point. The signal from photodetector 14a is relayed to the control system. By means hereinafter described, the time elapsed for the oil to go from point 9 to point 8 is then translated into centistokes.

The dimensions of capillary tube 2 and the volume of the section between timing points 8 and 9 are designed to provide direct reading in terms of centistokes on the particular type of timing mechanism used. In one instance, the viscometer was designed for use with a counter measuring in units of 0.01 second. In another instance, the viscometer was designed for use with a high 4speed printer-counter measuring in units of 25 cycles per second. Calibration in each instance was designed so that the counter would read out directly in terms of ,centistokes In the present viscometer, the capillary sizes and shapes are chosen to operate in the stream-line flow region so that linearity between viscosity and time is maintained.

f To measure samples covering a range of vlscosities 1n about the same time, three different size capillary tubes are employed. For example, one unit employed covered the range from l() centistokes to 500 centistokes. The design of capillary and efflux times chosen is also governed by the type of data recorder employed. The viscometer unit shown in the drawings employs a data recorder which is capable of accepting 25 cycles per second impulses. For recording devices with greater speed of response, it would be possible to decrease efliux times. This would require a redesign of the capillary tube. For example, withv a recording device capable of accepting 100 cycles per second impulses, and a capillary with a, bulb volume of 1A the size shown and described herein, the efux time would be reduced by Ia factor of four.

At the conclusion of the measurement, -sample bottle 4 is removed and, as will be shown in connection with FIGURE 4, a sump or drain pan is raised under the dip tube portion 6 of viscometer tube 2. The sump or drain pan 91 is raised until contact is made with the bottom edge of a cylinder or collar (not shown) which surrounds and extends beyond the dip tube portion 6 of viscometer 2, .and is designed to protect the dip tube from possible breakage by contact with the sump. Solvent solenoid valve 19 is opened and solvent, usually a light naphtha, is introduced into the system through line 18, and flows for a period of about 2 minutes through the capillary tube 2 for lthe purpose of dissolving oil and removing it from' the inner surfaces of the capillary tube 2. At the same time, a solvent solenoid valve (not shown) is also opened and solvent from the same `pump supplying solvent to solvent solenoid valve 19 is pumped through a series of jets surrounding the outside of the dip tube portion 6 of the viscometer tube 2. This is for the purpose of removing oil from the outer surface of dip tube 6, thus preventing this oil from becoming mixed with the next oil sample. The solvent-oil mixture is allowed to go into the'drain pan and is discarded. Usually, better cleaning results are attained if a pulse pump Vis used to pump the solvent into the system since t-he additional solvent turbulence from use of such a pump seems to give a somewhat 'better cleaning action than the Vuse of uniformly owing solvent.

After about two minutes of solvent washing, solenoid valve 19 is closed and solenoid valve 21 is opened permitting nitrogen, carbon dioxide, or some other inert gas to tlow through viscometer tube 2 in order to remove from the system all solvent vapors. At the same time that solenoid valve 21 is opened, another inert gas solenoid valve (not shown) is also opened, permitting nitrogen, carbon dioxide, or some other inert gas to flow through the series of jets surrounding the outside of the dip tube portion 6 of the viscometer tube 2. This cleaning cycle is accomplished in about two minutes, vafter which the solenoid valve 21 is closed (as well as the valve controlling the jets) and the viscometer unit is then ready to receive the next sample.

FIGURE 2 illustrates schematically, the `arrangement of manifold 17 of FIGURE l. Although FIGURE 2 illustrates the manifold head 35 in square arrangement, the head and conduits are usually circular in arrangement, in practice. For using the viscometer tube 2, as previously described, it is desirable that the manifold inlets, exits, and connections be made as short 4as possible. The positioning of the various solenoids for their particular uses is conveniently arranged so that in order of nearness to the inlet to tube 2 they are vent opening, vacuum outlet, solvent inlet and finally inert gas inlet. Opening 41 feeds into the top of viscometer tube 2 so that in that portion of the cycle as previously explained in connection with FIGURE 1l, inert gas such as nitrogen, carbon dioxide or air is introduced by means of line 42 through open solenoid valve 37 and then by means of conduit 36 is introduced into the top of viscometer tube 2 through opening 41. In other Words, the inert gas travels the complete length of the manifold conduit 36. Solvent inlet tube 43 which is controlled by solenoid valve 38 travels approximately only threefourths of the length of manifold tube 36 before it is introduced into the viscometer tube 2 by means of opening 41. The application of vacuum to the viscometer tube 2 is by means of solenoid valve `39 and vacuum outlet line 44. Solenoid vent valve 40 and the opening to the atmosphere through line 45 is closest to the viscometer tube 2 and the opening 41 to the viscometer tube 2.

The correlation of the valves in lFIGURE 2 with the valves in FIGURE 1 is as follows: vacuum valve 25 of FIGURE l corresponds to the solenoid vacuum valve 39 of FIGURE 2. Vent valve 23 of FIGURE l corresponds to solenoid vent valve 40 of FIGURE 2.; inert gas valve 21 of FIGURE l corresponds to solenoid gas valve 37 of FIGURE 2 and nally solvent valve 19 of FIGURE l corresponds to solenoid solvent valve 38 of FIGURE 2.

FIGURE 3 is partly schematic `and partly in section and shows an elevational view of the manifold lhead arrangement 35 along the line III-III of FIGURE 2. `Only solenoid valves 38 and 39 are shown in the figure together with the accompanying inlet 4and exit lines 43 and 44 respectively. FIGURE 3 does, however, show the arrangement whereby manifold conduit 36 is connected to viscometer tube 2 by means of a'ball 47 which is integral with the viscometer tube and a socket 48 which is integral with conduit 36 and outlet 41. A groove in the ball portion 47 is adapted to receive and hold an O ring 46 which acts as the seal between the ball 47 and the socket 48 so that the vmanifold may be readily disconnected from viscometer tube 2 at this ball and socket connection. Alternatively, the` groove may be in the socket 48 instead of the ball portion 47. Solenoid valves 38 and 39 are identical in construction. They contain springs 51 and 54 which tend to keep the valves closed. The seats rest upon the main portion of the valve or valve bases 49 and 52 respectively. These valves operate' so that when actuated by electric current the valve portions rise against the tension of springs 51 and 54 and remain open so that the washers 50 and 53 remain away from the orifices until such time as the current is turned ott, at which time the springs 51 and 54 again operate to seat the valves 49 and 52 in closed position.

FIGURE 4 represents in schematic form somewhat the same representation as is shown in FIGURE 1 but, in addition, the positioning of the control chassis 69 is shown and the hydraulic system for lifting sample bottles so that the liquid contained therein is in contact with the lower portion of the dip tube 6 is also shown. Additionally, the hydraulically operated drain pan 91 for receiving and removing from the system the waste solvent and residual oil preparatory to carrying out the next determination is 'also shown. The details of the control chassis 60 are shown in FIGURES 7, 8, and 9. Solenoid valves 19, 21, 23, and 25 are the same as those of like number illustrated in FIGURE 1. Similarly, lines 18, 20, 22, and 24 are identical with those in FIGURE 1. APulse pump 63 is shown in line 18 and regulator valve 62 is shown in the inert gas (nitrogen) inlet line 20. In vacuum line 24, the manostat or variable vacuum regulating valve 61 is shown. Electrical connections 64, 65, and 66 will be more fully explained and their significance with respect to control chassis 60 will be more fully understood by reference to FIGURE 7.

The details of the print control circuit are to be found in FIGURE 8 and electrical impulses from the control chassis 60 are connected and joined with the mechanism of the print control circuit through connections 67 and 68. Interlock circuits necessary for the simultaneous operation of multiple units are not shown, but it is contemplated to so operate a plurality of automatic viscometers in commercial yusage for -most etcient utilization of the novel devices.

Referring now to FIGURE 4, after the oil has `been drawn up into the viscometer tube 2 and the iinal timing determination is ready to be made, hydraulic uid is pumped, by means of pump 81, through lines 82, 80, and 85, through solenoid valve 79, actuated from control chassis 6i) and through line 88, so that piston 93 which controls lift 94 moves downwardly to lower the sample bottle. Previously, the direction of movement of piston 93 was upwardly at the time the sample was to be withdrawn from the sample bottle 4. After the sample bottle has been lowered suticiently to clear the sump and drain pan 91, solenoid valve 77 is opened and hydraulic iiuid iiows through lines 83 and 86 to actuate piston 89 which rotates the drain pan 91 in a vertical axis, so that it swings under the dip tube 6 at the lower portion of the viscometer tube 2. The height of the drain pan or sump 91 having drain connection 92 is controlled by piston 90 and the previously mentioned collar (not shown) surrounding dip tube 6, and piston 90 is actuated by hydraulic fiuid entering the piston through lines 84 and 87 and controlled by solenoid valve 7S. It will be appreciated that the hydraulic pistons have connections so that by use of three-way valves at 77, 78, and 79, fiuid may be introduced into the pistons to either extend the piston rod or to retract the piston rod so that there is a positive two-way movement of the lift 94, of the drain pan 91, and of the height of drain pan 91.

FIGURE represents schematically a diagram of the use of the automatic viscometer in a wholly automatic operation wherein the viscosity of the same oil sample is determined at two different temperatures and the viscosity in centistokes is either read on a register, is printed directly onto a tag or is printed directly onto a label attached to the sides of the sample bottle. Sample bottle 4 containing the oil whose viscosity is to be determined at two dif-ferent temperatures moves onto lift 94 by means of conveyor belt 95. Piston v93 then operates to raise the lift 94 sufiiciently high that sample bottle 4 is positioned with the dip tube 6 of viscometer 2 below the oil level in the sample bottle 4 after which the sequence of steps previously described with respect to FIGURE 1 occurs. As depicted in FIGURE 5, the viscosity determination at F. is made, after which the sample bottle 4 is lowered by means of lift 94 to the same position or plane as conveyor 94, i.e. its original position, and, upon completion of the measuring cycle, conveyor 96 then carries sample bottle 4 to the position 98 where the printing of the sample label or where the recording in centistokes is made. The bottle then, by means of conveyor 96, is carried onto lift 94a which operates in exactly the same manner with respect to viscometer tube 2a as was the case first described. The only difierence between the sequence of operation of a viscosity determination in the case of the tube 2a is that the temperature, for example, will be a different one from that originally used, usually this temperature is 210 F. In that instance, as previously described, detectors 14a, 15a, and 16a are actually located outside of the constant temperature bath and they receive the light measurements from lights 14, 15, and 16, which may also be outside of the bath, by means of light tubes which are either quartz or Lucite and which are enclosed in watertight copper or brass sheaths. The operation of sumps or drain pans 91 and 91a is as previously described with respect to those pans with reference to FIG- URE 4. Piston 93a then recedes with sample bottle 4 on the lift `94a and when the next bottle containing an oil sample is positioned onto lift 94a, sample bottle 4 is removed to the conveyor belt 97 where it again is stopped in position 99 to receive the viscosity information in centistokes from the printing stage 99. As previously stated, this information can be printed directly on a label attached to the side walls of the sample bottle, it may be printed on a tag attached to or to be attached to the sample bottle, or it can be visually read and recorded by an operator. Once this determination has been compieted, conveyor 97 removes sample bottle 4 from the automatic viscometer installation.

FIGURE 6 illustrates schematically one method employed for printing directly on the pressure sensitive labels attached to the sides of the sample bottles, the viscosity determination data in centistokes, at the stages 98 and 99 of FIGURE 5. Electrical connections 67 and 68 in the control chassis 106 are directly connected to like numbered lines shown in FIGURE 4 as being connected to control chassis 60. In the schematic illustrations shown in FIGURE 6, sample bottle 4, which is resting on either convevor 96 or 97, stops at either print position 98 or 99. This places the sample bottle 4 in the position shown in FIGURE 6. During the timing cycle, i.e. when the oil is between the marks 8 and 9 on viscometer tube 2, the high speed counter 102 through its relays 103 and by means of the print control chassis 104 supplied from power unit 105 through line 114 is recording and registering directly in centistokes, the viscosity of the oil being measured. Of course, registration of the counting starts when the oil reaches point 9 and stops when it reaches point 8, after which the recorded counter-printer 116 is pressed against pressure sensitive label wrapper 115 around sample bottle 4. The bottle 4 of course is on the conveyor belt 96 or 97, and in order to record the data on wrapper 115 air pressure is employed in pneumatic piston 100 containing pneumatic arm 101. In turn, piston rod 1011 containing print shoe is extended so that shoe 110 presses the bottle 4 against the counter-printer 116 after which the air pressure is released and arm 101 recedes, allowing the free bottle to continue its movement on the conveyors 96 or 97 as the case may be. Generator 19-7 operates, by means of connection 112, switch tubes in the control chassis 106 which in turn actuates the print control chassis 104 by means of electrical connections 10S and 109. The operation of this particular circuit is more fully hereinafter explained with reference to FGURE 8.

The successful operation of the automatic viscometer is dependent upon the principle that a light beam passing through tube 2 and striking the photodetectors 14a, 15a, and 16a tends to concentrate or decrease in intensity by the passing through the oil in viscometer tube 2, i.e., the light is focused on the photodetectors by the column of oil acting as a lens or if opaque or dark oils are present by the scattering of the light intensity present in the empty capillary tube. Conversely, the light striking the photodiode tubes when oil is not present between the light source and the particular detector tube tends to diiiuse and thus decrease in intensity in the case of light colored oils and vice versa in the case of dark or opaque oils in the second instance. The operation of the present invention is dependent upon this change in light intensity.

When the system is ready to inaugurate a viscosity determination there is, of course, no oil in the tube and there is no sample bottle immediately bel-ow the tube. Under such conditions and referring now to FIGURE 7, a more ldetailed description of control chassis 60 is now set forth. The bottleup switch 124 is in the ofi position and the bottledown switch 125 is likewise in the ott position. Similarly, all electrical energizing of solenoid valves 19, 21, 23, and 25 is off. Sample bottle 4 is placed in position under the bottom of viscometer tube 2 and the Itube immersed in the oil sample as shown in FIGURE 1 by operation of pis-t0n 93 as shown in FIG- URE 4. Bottleup switch 124 is turned on. This pulls in an-d locks in (electrically) t-he main power relay 123. Power flows through power relay 120' to va-cuum solenoid 25. Vacuum applied to` the tOp of viscometer tube 2 draws oil up into the tube. Clear light colored oil passing the bottom detector 14a and point 8 causes an increase in current in detector 14a, ampliiiers 14b and 14C and actuates sensitive relay 14d. The oil continues to rise. Oil passing middle detector 15a and point 9 causes an increase in current in detector 15a and -ampliiiers 15b and 15C and pulls in sensitive relay 15d. As the oil continues to rise, its meniscus passesthe top detector 16a and point causing an increase in current in detector 16a and ampliers 16h and 16C and thus pulls in sensitive relay 16d. Sin-ce relays 14d and 15d are closed, the action of 4relay 16d pulls in power relay 120 and it locks in electrically. The action of relay 120 turns vacuum solenoid 2S oit and turns vent solenoid 23 on. The action o-f relay 120" also actuates vent lock-out ready relay 121 which locks itself in electrically. The vent solenoid 23 being actuated, allows the oil to drop in tube 2. As the oil leaves to-p detector 16a and the current decreases in ampliiiers 1619 `and 16C, sensitive relay 16d drops out but relay 120 does not drop out because of electrical lock-in. As the oil continues to drop and leaves middle detector a and the current decreases in amplifiers 15b and 15e, sensitive rel-ay- 15d drops out but there is no action of relay 120 or relay 121 due to electrical interlocking. As the oil continues to drop and leaves the bottom detector 14a and the current is reduced in ampliiiers 1417 and 14e, sensitive relay 14d drops out. This causes relay 120v to drop out and vent lockout relay 122 to pull in and electrically lock in. The action of relay 120 turns the vent solenoid 23 oli and vacuum `solenoid 25 on Vacuum is once again applied to the top of tube 2 causing the oil to rise again in tube 2. Oil passing bottom photodetector 14a causes -an increase in current at photodetector 14a and through amplifiers 14b and 14e` and sensitive relay 14d is pulled in Due to electrical interlocking this has no effect on the system; The higher current through relay amplifier 14o causes positive voltage to appear at control point B (line 68) of count gate control ampliiier 126. Appearance of oil at the middle photodetector 15a increases current in arnpliers 15b and 15e and pulls in sensitive relay 15d. Due to electrical interlocking this has no eiect on the system. Higher current in relay lamplifier 15C causes positive voltage to appear at control point A (line 67) of count lgate amplifier 126. When the oil once again reaches the top detector 16a causing increased current in amplifiers 1Gb and 16C, sensitive relay 16d is pulled in This actuates power relay which turns vacuum solenoid 25 oli but due to the lock-out action of relay 122 the vent remains closed. The oil stops in the viscometer tube 2 just above the top detector 16a. At this point in .the cycle, soak timer 129 and bottledown timer 130 are actuated by the functions of relays 120 and 122. After one minute (or any preselected time interval) the bottledown timer 130 turns on bottledown indicator light 131. At this point the sample bottle 4 should be dropped below tube 2 so that the -dip tube 6 of tube 2 does not touch the surface of the oil in `the sample bottle 4. Bottledown switch 125 should be turned on and bot-tleup switch 124 should be turned oli Soak timer 129 runs for about 3 minutes to allow the oil to come to equilibrium temperature with the temperature of the constant temperature bath 3. A-fter about 3 minutes, soak timer 129 actuates vent release relay 128 and counter arm relay 132. Vent release relay 128 actuates vent solenoid 23 and allows -oil to drop in tube 2. Counter arm relay 132 prepares the counting system for operation. Oil leaving the top detector 16a reduces the current in aimpliiiens 16h yand 16C and drops out sensitive relay 16d. By relay 16d dropping out, the complete system will be allowed to drop out at end of the time measuring cycle.

Oil leaving the middle detector 15a reduces the current in amplifiers 15b and 15C and drops out sensitive relay 15d. The operation of sensitive relay 15d has no effect :but opens the system drop out loop. Reduced current in amplifier 15C causes the voltage at control point A (line 67 on count gate control ampliiier 126 to drop to Zero. (Since control voltage B (line 68) is positive yand counter arm relay 132. is actuated, the counting (measurement) system is actuated as more fully hereinaiiter `described in connection with FIGURE 8.) Oil leaving the bottom detector 14a reduces the current in lampliiiers 14b and 14C and drops out sensitive relay 14d. Sensitive rel-ay 14d drops out the main power interlock loop through main power drop out relay 127 and the system returns to its lstarting condition. The -reduced current in amplifier 14C causes the voltage at control point B (line 6%) of the count gate amplifier 126 to drop to zero. This stops the counter operation and completes the actual viscosity time measurement.

FIGURE 8 shows the control arrangement for the conversion of the signals of FIGURE 7 into data relating to viscosity. In the conversion of the measurement signals, above discussed, to the printing of the data from those signals, a basic timing pulse is irst generated by a 200 cycles per second tuning fork 133 (accuracy l part in 100,000). Frequency is divided by a series of 3 binaries (flip-flops) 134, 135, and 136 to supply 25 cycles per second to the input side of the count gate amplifier 126. Items 133, 134, 1.35 and 136 together are shown as 107 in FIGURE 6. Items 126 and 13-7 together constitute 106 of FIGURE 6. There is a constant input of 25 cycles per second square wave voltage to count gate ampliiier 126, so that the appearance of a signal at the output of amplifier 126 depends on the voltages present at control points A and B (lines 67 and 68 respectively of FIG- URE 4) from amplifiers 15C and 14C of FIGURE 7. Output Will appear from amplifier 126 only when control voltage A (line 67 is zero and control voltage B (line 68) is positive. Since this condition occurs during the charging and conditioning cycle, the counter system is prevented from operating through the action of counter arm relay/132 and amplifier -lswitch tube 137. Ampliiier -1- switch tube 137 will only produce output to the power ampliiier 138 when counter arm relay 132 has been actuated after the 3 -minute temperature equilibrium part of the cycle. Oil passing the middle detector 15a causes control voltage A (line 67) to drop to zero, amplifier 126 passes the 25 cycles per second signal to amplifier 137. With relay 132 on, amplifier 137 passes the signal to power amplifier 138. Power amplifier 138 in turn actuates millisecond relay 139 (together shown as 104 in FIGURE 6) which turns counter power 140 (105 in FIGURE 6) o and on, and thus actuates counter/ printer coil 141 (102 in FIGURE 6). When oil passes the bottom detector 14a, control voltage B (line 68) drops to zero and the 25 cycles per second output from count gate amplifier 126 stops and the counter stops. When charging equipment (FIGURE 7) drops out, counter arm relay 132 drops out. This action starts print timer 143 which puts power on print shoe 142 to cause mechanical printing action. After about seconds the print timer 143 drops the power from the print shoe 142 and starts the reset timer 144. After about 20 seconds, the reset timer actuates the reset pulse power 146 causing reset motor 145 to be operated. The system returns to normal at the end of the reset period and the cycle is repeated on the next sample determination. After measurement is complete, sample bottle 4 is removed from below measuring tube 2 and the drain pan 91 is placed in position under the tube.

Referring now to FIGURE 9, cleaning switch 147 is turned on. This actuates solvent timer 148 and solvent solenoid 19 which allows suitable solvent to enter the upper end of viscometer tube 2. As previously described, the solvent timer 148 allows solvent to flow for about 2-3 minutes. At the end of this period, the inert gas (nitrogen) timer 149 is actuated as the solvent timer 14S goes off Solvent timer 14-9 turns on the nitrogen solenoid 21 which allows nitrogen or other inert gas under slight pressure to flow through the viscometer tube 2 for about 2-3 minutes to evaporate all of the solvent and dry the tube. After the 2-3 minute period of operation of inert gas timer 149, the cleaning cycle is shut down automatically and the cleaning switch 147 may be turned off and another sample determination may be started.

The novel automatic viscometer herein described can also be applied to a system which is directly connected to a pipe line in a refinery so that either at prearranged intervals of time or, as desired, samples of the oil within the pipe line may be withdrawn and their viscosity automatically determined without actually removing a sample from the pipe line system. This is accomplished by simply tapping the pipe line with a three-way valve and allowing a portion of the oil in the pipe line to proceed through a by-pass, the by-pass line being, in turn, directly connected to dip tube 6 of the automatic viscometer. By the application of vacuum through the regulation of the by-pass valve, it is possible to maintain a controlled fiow of oil in the by-pass line and to subject the sample of oil so withdrawn to an automatic viscosity determination in the novel apparatus.

The particular viscometer disclosed in FIGURE l was designed for determining viscosities of oils having a viscosity range between about 10 and about 300 centistokes at 100 F. and iiow times of between about l0 and about 300 seconds and for determining viscosities of oils of about 2 to 100 centistokes at 210 F. with flow time measurements ranging from about 2O to about 1000 seconds. Obvious modifications of the Atlantic type viscometer while still employing the principles of the present invention are readily apparent and are within the purview of the invention hereindescribed.

Having now thus fully described and illustrated the character of the invention, what is desired to be secured by the Letters Patent is:

1. An automatic viscometer which comprises (1) a vertical, light transparent capillary tube, (2) a first light source positioned near the lower end of said capillary tube and disposed to transmit light beams substantially transversely throughv at least a portion thereof, (3) a first photoelectric cell positioned to receive light beams from said first light source after passing through at least a portion of said capillary tube, said first light source and said first photoelectric cell together constituting a first detector pair, (4) a second detector pair positioned at a middle location with reference to said capillary tube, (5) a third detector pair positioned at an upper location with respect to said capillary tube, (6) a first conduit connected to said capillary tube above said third detector pair wherethrough said tube may be evacuated to draw up thereinto a liquid of which the viscosity is to be determined, (7) valve means in said first conduit whereby the passage through said first conduit may be substantially completely closed, (8) a second conduit connected to said capillary tube above said third detector pair wherethrough said tube may be vented to let fall therein a liquid of which the viscosity is to be determined, (9) valve means in said second conduit whereby the passage through said second conduit may be substantially cornpletely closed, a manifold whereby the first and second conduits may be selectively connected to the capillary tube, (10) first and second series of amplifiers and relays adapted to convert electrical input signals into lapsed time data, (ll) electrical connections between the photoelectric cells of said first and second detector pairs and said first and second series of amplifiers and relays whereby input signals corresponding to output signals from the photoelectric cells of said first and second detector pairs may be imposed upon said first and second series of amplifiers and relays, (l2) electrical actuating means operatively connected to said valve means in said first and second conduits, (13) a third series of amplifiers and relays adapted to convert electrical input signals into power outputs, said third series of amplifiers and relays being connected to said electrical actuating means to impose said power outputs thereupon whereby said valve means in said first and second conduits may be actuated in directions to close the passage through said first conduit and open the passage through said second conduit, and (14) electrical connections between the photoelectric cell of said third detector pair and said third series of amplifiers and relays whereby input signals corresponding to output signals from the photoelectric cell of said third detector pair may be imposed upon said third series of amplifiers and relays.

2. An automatic viscometer according to claim 1 which comprises further (15) a third conduit connected to said capillary tube above said third detector pair wherethrough said tube may be fiushed out with solvent liquid, (16) valve means in said third conduit whereby the passage through said third conduit may be substantially cornpletely closed, (17) a fourth conduit connected to said capillary tube above said third detector pair wherethrough said tube may be blown out with inert gas, (18) valve means in said fourth conduit whereby the passage through said fourth conduit may be substantially completely closed, a manifold whereby the first, second, third and fourth conduits may be selectively connected to the capillary tube and (19) electrical actuating means operatively connected to said valve means in said third and fourth conduits to cause said capillary tube to be flushed out with solvent liquid and then blown out with inert gas.

3. An automatic viscometer according to claim l which comprises further a counter-printer circuit and mechanism connected electrically to said first and second series of amplifiers and relays, and adapted to convert lapsed time data therefrom into printing surfaces giving a reading of liquid viscosity in selected units.

4. An automatic viscometer according to claim 1 which comprises further a first positioning means in spaced, operative relation to said capillary tube whereby vessels containing liquid of which the viscosity is to be determined may be raised and lowered to bring said liquid into and out of contact with the lower end of Said tube.

An automatic viscometer according to claim 4 which comprises further a second positioning means in spaced, operative relation to said capillary tube, said second positioning means including a drain pan and being adapted to move said drain pan into -and out of liquid-catching alignment with said capillary tube below the lower end of said tube.

6. A process for automatically measuring the viscosity of a liquid which comprises the steps of (l) drawing up a column of said liquid from a body thereof in a container Vessel into a transparent capillary tube by the application of vacuum to said tube to carry the meniscus of said column successively through first, second, and third light beams directed respectively toward first, second, and third photoelectric cells; (2) using the output signal from said third photoelectric cell after passage through said third light beam of the meniscus of said column in rising motion to terminate the application of vacuum to said tube and vent said tube to allow said column to descend therein, using the output signal from said first photoelectric cell after the passage through said first light beam of the meniscus of said first column in descending motion to terminate the venting of said tube and reapply vacuum thereto to dr-aw up a second column of said liquid thereinto to carry the meniscus of said second column through said third light beam, using the output signal from said third photoelectric cell after passage through said third light beam of said second column in rising motion to terminate the application of vacuum to said tube, and (3) using the output signals from said second and first photoelectric cells after passage through said second and first light beams of the meniscus of said column in descending motion to generate lapsed time data signals.

7. A process for automatically measuring the viscosity of a liquid according to claim 6 which comprises further the steps of draining said column of said liquid completely out of said capillary tube after the meniscus of said column has passed through Said first light beam in descending motion; thereafter flushing out said tube with solvent liquid, and thereafter blowing out said tube with inert gas.

8. A process for `automatically measuring the viscosity of a liquid which comprises the steps of (l) positioning a container vessel and a body of said liquid therein below the lower end of a transparent capillary tube, and elevating said container vessel relative to said tube to immerse the lower end of said tube in said body of liquid; (2) drawing up a first column of said liquid into said tube by the application of vacuum thereto to carry the meniscus of said first column successively through first, second, and third light beams directed respectively toward first, second, and third photoelectric cells; (3) using the output signal from said third photoelectric cell after passage through said third light beam of the meniscus of said first column in rising motion to terminate the application of vacuum to said tube and Vent said tube to allow said first column to descend therein; (4) using the output signal from said first photoelectric cell after the passage through said first light beam of the meniscus of said first column in descending motion to terminate the venting of said tube and reapply vacuum thereto to draw up a second column of said liquid thereinto to carry the meniscus of said second column through said third light beam; (5) using the output signal'from said third photoelectric cell lafter passage through said third light beam of said second column in rising motion to terminate the application of vacuum to said tube, lower said container vessel to bring the surface of that portion of said body of liquid still remaining therein below the lower end of said tube, and vent said tube to allow said second column to descend therein, and (6) using the output signals from said second and first photoelectric cells after passage through said second and first light beams of the meniscus of said second column in descending motion to generate lapsed time data signals.

9. A process for automatically measuring the viscosity of a liquid at at least two temperatures which comprises the steps of (l) positioning a container vessel anda body of said liquid therein below the lower end of a first transparent capillary tube, and elevating said container vessel relative to said first tube to immerse the lower end of said first tube in said body of liquid; (2) drawing up a first column of said liquid into said first tube by the application of vacuum thereto to carry the meniscus of said first column successively through first lower and upper light beams directed respectively toward first lower and upper photoelectric cells; (3) holding said first column by vacuum in said first tube for a first determinate period of time with the meniscus of said first column above said first upper light beam, and during this period maintaining at least part of said first tube at a first predetermined temperature, said first determinate period of time being sufficiently long for said first column of liquid to assume essentially said first predetermined temperature; (4) lowering said container vessel to bring the surface of that portion of said body of liquid still remaining therein -below the lower end of said first tube and positioning said container vessel and said remaining liquid body portion below the lower end of a second transparent capillary tube; (5) venting said first tube to allow said first column of liquid therein to descend; (6) using the ouput signals from said first upper and lower photoelectric cells after passage through said first upper and lower light beams of the meniscus of said first column in descending motion to generate lapsed time data signals; (7) elevating said container vessel relative to said second tube to irnmerse the lower end of said second tube in said remaining liquid body portion; (8) drawing up a second column of said liquid into said second tube by the application of vacuum thereto to carry the meniscus of said second column successively through second lower and upper light beams directed respectively toward second lower andupper photoelectric cells; (9) holding said second column t by vacuum in said second tube for a second determinate period of time with the meniscus of said second column above said second upper light beam, and during this period maintaining at least part of -said second tube at a second predetermined temperature, said second determinate period of time being sufficiently long for said second column of liquid to assume essentially said second predetermined temperature; (10) lowering said container vessel to bring the -surface of that portion of said body of liquid still remaining therein below the lower end of said second tube; (1l) venting said second tube to allow said second column of liquid therein to descend, and (12) using the output signals from said second upper and lower photoelectric cells after passage through said first upper Iand lower light beams of the meniscus of said second column in descending motion to generate lapsed time data signals.

References Cited in the file of this patent UNITED STATES PATENTS y2,252,014 Lupfer Aug. 12, 1941 FOREIGN PATENTS 519,112 Great Britain Mar. 18, 1940 OTHER REFERENCES by Jones et al, (Copy in 73-55.) 

1. AN AUTOMATIC VISCOMETER WHICH COMPRISES (1) A VERTICAL, LIGHT TRANSPARENT CAPILLARY TUBE, (2) A FIRST LIGHT SOURCE POSITIONED NEAR THE LOWER END OF SAID CAPILARY TUBE AND DISPOSED TO TRANSMIT LIGHT BEAMS SUBSTANTIALLY TRANSVERSELY THROUGH AT LEAST A PORTION THEREOF, (3) A FIRST PHOTOELECTRIC CELL POSITIONED TO RECEIVE LIGHT BEAMS FROM SAID FIRST LIGHT SOURCE AFTER PASSING THROUGH AT LEAST A PORTION OF SAID CAPILLARY TUBE, SAID FIRST LIGHT SOURCE AND SAID FIRST PHOTOELECTRIC CELL TOGETHER CONSTITUTING A FIRST DETECTOR PAIR, (4) A SECOND DETECTOR PAIR POSITIONED AT A MIDDLE LOCATION WITH REFERENCE TO SAID CAPILLARY TUBE, (5) A THIRD DETECTOR PAIR POSITIONED AT AN UPPER LOCATION WITH RESPECT TO SAID CAPILLARY TUBE, (6) A FIRST CONDUIT CONNECTED TO SAID CAPILLARY TUBE ABOVE SAID THIRD DETECTOR PAIR WHERETHROUGH SAID TUBE MAY BE EVACUATED TO DRAW UP THEREINTO A LIQUID OF WHICH THE VISCOSITY IS TO BE DETERMINED, (7) VALVE MEANS IN SAID FIRST CONDUIT WHEREBY THE PASSAGE THROUGH SAID FIRST CONDUIT MAY BE SUBSTANTIALLY COMPLETELY CLOSED, (8) A SECOND CONDUIT CONNECTED TO SAID CAPILLARY TUBE ABOVE SAID THIRD DETECTOR PAIR WHERETHROUGH SAID TUBE MAY BE VENTED TO LET FALL THEREIN A LIQUID OF WHICH THE VISCOSITY IS TO BE DETERMINED, (9) VALVE MEANS IN SAID SECOND CONDUIT WHEREBY THE PASSAGE THROUGH SAID SECOND CONDUIT MAY BE SUBSTANTIALLY COMPLETELY CLOSED, A MANIFOLD WHEREBY THE FIRST AND SECOND CONDUITS MAY BE SELECTIVELY CONNECTED TO THE CAPILLARY TUBE, (10) FIRST AND SECOND SERIES OF AMPLIFIERS AND RELAYS ADAPTED TO CONVERT ELECTRICAL INPUT SIGNALS INTO LAPSED TIME DATA, (11) ELECTRICAL CONNECTIONS BETWEEN THE PHOTOELECTRIC CELLS OF SAID FIRST AND SECOND DETECTOR PAIRS AND SAID FIRST AND SECOND SERIES OF AMPLIFIERS AND RELAYS WHEREBY INPUT SIGNALS CORRESPONDING TO OUTPUT SIGNALS FROM THE PHOTOELECTRIC CELLS OF SAID FIRST AND SECOND DETECTOR PAIRS MAY BE IMPOSED UPON SAID FIRST AND SECOND SERIES OF AMPLIFIERS AND RELAYS, (12) ELECTRICAL ACTUATING MEANS OPERATIVELY CONNECTED TO SAID VALVE MEANS IN SAID FIRST AND SECOND CONDUITS, (13) A THIRD SERIES OF AMPLIFIERS AND RELAYS ADAPTED TO CONVERT ELECTRICAL INPUT SIGNALS INTO POWER OUTPUTS, SAID THIRD SERIES OF AMPLIFIERS AND RELAYS BEING CONNECTED TO SAID ELECTRICAL ACTUATING MEANS TO IMPOSE SAID POWER OUTPUTS THEREUPON WHEREBY SAID VALVE MEANS IN SAID FIRST AND SECOND CONDUITS MAY BE ACTUATED IN DIRECTIONS TO CLOSE THE PASSAGE THROUGH SAID FIRST CONDUIT AND OPEN THE PASSAGE THROUGH SAID SECOND CONDUIT, AND (14) ELECTRICAL CONNECTIONS BETWEEN THE PHOTOELECTRIC CELL OF SAID THIRD DETECTOR PAIR AND SAID THIRD SERIES OF AMPLIFIERS AND RELAYS WHEREBY INPUT SIGNALS CORRESPONDING TO OUTPUT SIGNALS FROM THE PHOTOELECTRIC CELL OF SAID THIRD DETECTOR PAIR MAY BE IMPOSED UPON SAID THIRD SERIES OF AMPLIFIERS AND RELAYS. 